The present invention relates to batteries of a form where a circuit board is integrated with a battery cell by a resin mould section.
As shown in FIG. 9, battery 51 is a conventional battery for use in portable terminals such as cell phones, simple portable telephones and the like.
This battery 51 comprises a rectangular tabular battery cell 52, a circuit board 53 positioned along a side 52a of the battery cell 52, a resin mould section 54 fixed to sides 52a, 52b, and 52c of the battery cell 52, a cable 55 leading from the resin mould section 54, and a connection terminal 56 provided on the end of the cable 55.
The battery cell 52 is formed by enclosing an electrolyte together with a laminate of several layers of positive film and negative film separated by a separator, inside a container made by deep drawing aluminum or aluminum alloy. Also, as shown in FIG. 10, a negative electrode terminal 52d is positioned so as to protrude from the center of the side 52b of the battery cell 52, and the other surfaces of battery cell 52 form the positive electrode terminal.
The circuit board 53 is provided with electronic components 70 for charge control of the battery cell 52, and is attached to the side 52a of the battery cell 52. Furthermore, the circuit board 53 is connected to the positive electrode terminal and to the negative electrode terminal 52d of the battery cell 52 by metal connection plates 57 and 58.
These connection plates 57 and 58 are made of metal plate bent into an L-shape, and the circuit board 53 and the battery cell 52 are electrically connected by soldering their distal ends 57a and 58a to a rear face 53b of ends 53c and 53d of the circuit board 53, and soldering the other ends 57b and 58b to the negative electrode terminal 52d and the positive electrode terminal respectively.
Here, because the other end 57b of the connection plate 57 is positioned along the sides 52a and 52b of the battery cell, an insulation sheet 59 is provided between the battery cell 52 and the connection plate 57, so that the connection plate 57 does not contact and short with the sides 52a and 52b which constitute the positive electrode terminal.
These connection plates 57 and 58 are positioned so as to hold the battery cell 52, so that the circuit board 53 is fixed to the battery cell 52. Next, the circuit board 53 and connection plates 57 and 58 which are fixed to the battery cell 52, are enveloped by a resin mould section 54, and thus formed integral with the battery cell 52, as shown in FIG. 9.
The connection terminal 56 is for supplying power from the battery cell 52 to a portable terminal (not shown in the figure), by connecting to a connection terminal of the portable terminal, and is connected to the cable 55. The cable 55 is soldered to the front face 53a side of the end 53c of the circuit board 53, as shown in FIG. 10.
However, in the above mentioned battery 51, the positioning of the circuit board 53 in relation to the battery cell 52 is problematic, due to the circuit board 53 being connected by soldering to the side 52a of the battery cell 52 through the connection plates 57 and 58.
Furthermore, with regard to the recent demand for miniaturization of portable terminals, the existence of the cable 55 limits the extent to which miniaturization of the battery is possible.
Moreover, because the terminals of the battery cell 52 are connected to the portable terminal through the cable 55, this introduces an extra impedance between the battery cell 52 and the portable terminal, with the problem of a drop in power supply efficiency of the battery cell 52.